通过带有 DateTime 参数的 COM 调用方法导致找不到方法

Question

I'm trying to invoke a method from another DLL via a COM-server. When I pass an integer as argument (and change the method in the other dll to accept an integer) everything works fine. But when I try to pass a DateTime, it doesn't work and I get a method not found error. I have no idea why. Any ideas?

Note: the code calling the method is Visual Basic, the code on the 'receiving' end is C#.

This works:

Caller:

Dim ComType As Type = Type.GetTypeFromProgID("Scheduling.ComServer")
Dim ComObject As Object = Activator.CreateInstance(ComType)

Dim methodArgs As Object() = New Object(0) {}
methodArgs(0) = 10
Dim result As String = CStr(ComType.InvokeMember("ScheduleItems", BindingFlags.InvokeMethod, Nothing, ComObject, methodArgs))

Method in other dll:

public string ScheduleItems(int scheduleFrom)
{
    Scheduler scheduler = new Scheduler();
    return scheduler.ScheduleItems(new DateTime(2019, 11, 1));
}

This doesn't work:

Caller:

Dim ComType As Type = Type.GetTypeFromProgID("Scheduling.ComServer")
Dim ComObject As Object = Activator.CreateInstance(ComType)

Dim methodArgs As Object() = New Object(0) {}
methodArgs(0) = New DateTime(2019, 11, 1)
Dim result As String = CStr(ComType.InvokeMember("ScheduleItems", BindingFlags.InvokeMethod, Nothing, ComObject, methodArgs))

Method in other dll:

public string ScheduleItems(DateTime scheduleFrom)
{
    Scheduler scheduler = new Scheduler();
    return scheduler.ScheduleItems(scheduleFrom);
}

Answer 1

So it turns out it was working just fine after all...

Because the separate dll is... separate, I have to recompile it manually when I change it (it doesn't recompile when I run the calling application). And I forgot to do that when I changed the int to datetime. Goddamn it, now I lost 30 minutes and I feel stupid.